package org.apache.maven.repository.internal;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;

import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.deployment.DeployRequest;
import org.eclipse.aether.impl.MetadataGenerator;
import org.eclipse.aether.installation.InstallRequest;
import org.eclipse.aether.metadata.Metadata;

/**
 * @author Benjamin Bentmann
 */
class VersionsMetadataGenerator implements MetadataGenerator {

  private Map<Object, VersionsMetadata> versions;

  private Map<Object, VersionsMetadata> processedVersions;

  public VersionsMetadataGenerator(RepositorySystemSession session, InstallRequest request) {
    this(session, request.getMetadata());
  }

  public VersionsMetadataGenerator(RepositorySystemSession session, DeployRequest request) {
    this(session, request.getMetadata());
  }

  private VersionsMetadataGenerator(RepositorySystemSession session, Collection<? extends Metadata> metadatas) {
    versions = new LinkedHashMap<Object, VersionsMetadata>();
    processedVersions = new LinkedHashMap<Object, VersionsMetadata>();

    /*
     * NOTE: This should be considered a quirk to support interop with Maven's legacy
     * ArtifactDeployer which processes one artifact at a time and hence cannot associate the
     * artifacts from the same project to use the same version index. Allowing the caller to pass in
     * metadata from a previous deployment allows to re-establish the association between the
     * artifacts of the same project.
     */
    for (Iterator<? extends Metadata> it = metadatas.iterator(); it.hasNext();) {
      Metadata metadata = it.next();
      if (metadata instanceof VersionsMetadata) {
        it.remove();
        VersionsMetadata versionsMetadata = (VersionsMetadata) metadata;
        processedVersions.put(versionsMetadata.getKey(), versionsMetadata);
      }
    }
  }

  public Collection<? extends Metadata> prepare(Collection<? extends Artifact> artifacts) {
    return Collections.emptyList();
  }

  public Artifact transformArtifact(Artifact artifact) {
    return artifact;
  }

  public Collection<? extends Metadata> finish(Collection<? extends Artifact> artifacts) {
    for (Artifact artifact : artifacts) {
      Object key = VersionsMetadata.getKey(artifact);
      if (processedVersions.get(key) == null) {
        VersionsMetadata versionsMetadata = versions.get(key);
        if (versionsMetadata == null) {
          versionsMetadata = new VersionsMetadata(artifact);
          versions.put(key, versionsMetadata);
        }
      }
    }

    return versions.values();
  }

}
